Since 1624 the East India Company had established control on Formosa. Under its charge missionaries worked on the Christianization of the indigenous people: amongst them was doctor Antonius Hambroek. On April 30th 1661 Chinese-Japanse warlord Koxinga (Kok seng yâ) invaded the island, whereby Hambroek fell to Chinese hands. Fort Zeelandia remained under Dutch control. Koxinga decided to send Hambroek as a representative to meet with Coyett, commander of the fort, to convince him to surrender. In stead of demanding surrender, Hambroek urged Coyett to persist in battle. Hambroek decided to return to Koxinga, who beheaded him.